Author Topic: Air Force's "Next Generation Engine" program (RL10 replacement?)  (Read 46392 times)

Offline neilh

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Apparently the Air Force issued an RFI for their "Next Generation Engine" program a couple weeks ago, with responses due Nov 9. When I first started reading it, I assumed it was for something like ACES, but reading it through it's apparently for replacing (or upgrading?) the RL10s. The most surprising bit for me was the requirement for >465 isp.... only engine design I've heard of that meets that is the preliminary Raptor design (470 isp):

https://www.fbo.gov/index?s=opportunity&mode=form&id=d23c8a2ed2c27f3ce252c6e702a89a10&tab=core&_cview=0
http://spacenews.com/military/air-force-upper-stage.html

Quote
The purpose of this RFI is to seek information from domestic manufacturers capable of developing and manufacturing a new upper stage engine.

...


BACKGROUND:


The Atlas V and Delta IV upper stages currently employ two different variants of the RL10 rocket engine. While the RL10 engines meet current requirements, the Air Force anticipates needing a new engine produced and qualified NET 2017.


OVERVIEW OF OBJECTIVES:


The Air Force is seeking an upper stage engine utilizing modern design and manufacturing methods. It is expected that the new engine will demonstrate state-of-the-art operating margin and reliability and minimize life-cycle costs.


UPPER STAGE ENGINE TECHNICAL REQUIREMENTS


The engine will be a U.S. developed and manufactured LOX/LH2 rocket engine with a vacuum thrust in the range of 25k lbfs to 35k lbfs integratable with the upper stage of the EELV family of launch vehicles.


Additional top level technical requirements:


Isp (vacuum): 465 seconds or greater
Nozzle: Fixed (preferred, but not required)
Throttle: Throttlable down to 21,000 lbs (deeper throttle desired, but not required)
Restartable: Minimum of 4 flight starts
Life expectancy: 3000 seconds or greater
Reusable: Not required
Mixture Ratio: Adjustable during operation
Length (gimbal to nozzle exit): NTE 90 inches
Exit Diameter: NTE 73 inches (desired)
Threshold Reliability: 0.9990 or greater


UPPER STAGE ENGINE INFORMATION SOUGHT


The Air Force is asking for insight into the state of development of candidate solutions for upper stage engines, technology readiness levels (TRL), manufacturing readiness level (MRL), and critical technology risk reduction efforts.
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Offline Halidon

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Sadly, the SpaceX powerpoint from earlier this year have Raptor's vacuum thrust quite a bit higher than that. RL-60's even well above that. There was an RL-10B-X design back in the 90s that was supposed to hit those numbers.

Offline TrueBlueWitt

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Sounds like a great engine.. and about the right timing.. for SLS US/EDS!

Hopefully Human Rating is somewhere in design requirements as well.

Any possible tie-in with NASA's CECE work?
« Last Edit: 10/16/2010 03:38 am by TrueBlueWitt »

Offline Robotbeat

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That's great. RL-10 is an excellent (and cheap!) engine, a gem of American hydrolox engine design. I'm glad resources are going to having it being upgraded (or replaced with a similar but better engine). Money well spent.
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Offline MP99

Great find!

Of course, NGE is mentioned as a possible u/s engine for the >130mT option in HEFT2 (p.32), so it's great to see a few details. Interesting that it would have a smaller nozzle than RL-10B-2: 77" vs 87".

If this engine could produce 35klb, then a cluster of 4 would out-perform 6x RL-10B-2, and NASA's LOM calculation should also be improved. I suspect at least 6x NGE's would be required to achieve 130mT to orbit.


There are a few typos in the article:-

Quote
The RL-10B-2 engine used in the Atlas 5 Delta IV vehicle is more capable than its Delta 4 Atlas V counterpart, the RL-10A-4-2. The Atlas Delta variant produces 24,750 pounds of thrust and has a specific impulse — a measure of the engine’s efficiency — of 465.5 seconds. The Air Force would like the next-generation engine to be as efficient as the current Atlas ??Delta?? design

Quote
submit ideas for building a next-generation upper-stage engine to replace by No-Earlier-Than 2017 the two versions of the RL-10

===================

Quote
The United States Air Force (USAF) is seeking information from domestic manufacturers capable of developing and manufacturing a new upper stage engine for the EELV Program.

Probably excludes RL-60, then? (The thrust is in the wrong range, anyway).


That's great. RL-10 is an excellent (and cheap!) engine, a gem of American hydrolox engine design. I'm glad resources are going to having it being upgraded (or replaced with a similar but better engine). Money well spent.

Quote
While the engine has evolved over the years, Pratt & Whitney Rocketdyne officials say engineers are reaching the limit of additional improvements that can be squeezed out of the 50-year-old engine design.

Even assuming P&WR win the contract, it looks like more than minor tweeks to RL-10.


Quote
It is expected that the new engine will demonstrate state-of-the-art operating margin and reliability

If SOTA = minimum margins, then that's going to clash with NASA wanting 1.4 FOS for an HR'd version.

cheers, Martin

Offline fregate

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With all due respect - Raptor upper stage engine (LOX/LH2) would have a vacuum thrust 150,000 lbf.
This is a way out the range of 25k lbfs to 35k lbfs  ::)
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Offline robertross

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Sounds like a great engine.. and about the right timing.. for SLS US/EDS!

Hopefully Human Rating is somewhere in design requirements as well.

Any possible tie-in with NASA's CECE work?

I'm skeptical on that one, since they 'prefer' a fixed nozzle, but it's not a requirement, and clearly you would want a fixed nozzle for meeting HR reliability.

It lends to theories of DoD needing to launch larger payloads (around 2017), and to have one common EELV vehicle going forward.

Offline Jim

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It lends to theories of DoD needing to launch larger payloads (around 2017), and to have one common EELV vehicle going forward.

How so?

It says EELV upperstageS.   

Also, it doesn't necessarily mean large payloads.  If could do with trajectory shaping.

« Last Edit: 10/16/2010 03:53 pm by Jim »

Offline Ronsmytheiii

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It lends to theories of DoD needing to launch larger payloads (around 2017), and to have one common EELV vehicle going forward.

How so?




I am thinking it will probably more likely be for the next generation AF LV.

Offline TrueBlueWitt

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Sounds like they want RL-10B-2 performance in an RL-10A-4-2 package. 

How much would payloads to GTO increase for Atlas V with NGE?

I didn't see a mass target for the new engine.. did I miss something?

Jim.. would this be to retrofit existing US.. or for a new common(ACES?) US?

Offline Antares

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RL-10 is an (and cheap!) engine

NO, with the end of the SSME contract all of the prices are going through the roof.  Take what you knew and multiply by 4.
« Last Edit: 10/17/2010 01:22 am by Antares »
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Offline alexw

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Sounds like they want RL-10B-2 performance in an RL-10A-4-2 package. 
How much would payloads to GTO increase for Atlas V with NGE?
I didn't see a mass target for the new engine.. did I miss something?
Jim.. would this be to retrofit existing US.. or for a new common(ACES?) US?
   Effectively, both are possible and under consideration.

Read Barr & Kutter 2010 (pg.4):

Quote
ULA has been focusing on common Atlas and Delta upper stage upgrades as the next steps in our EELV evolution. Some confusion can exist because ULA is pursuing two separate upper stage upgrades. The Common Centaur is focused on the Air Force, NASA science, and commercial requirements with the goal of replacing the Delta IV 4m Upper Stage with the Centaur to achieve greater commonality and to realize cost savings across the EELV fleet. Tied to this upgrade is the rework of the large number of inventory RL10B-2 engines into a new common RL10C variant that captures the best of the B-2 and A-4, and can be used on Atlas V, and potentially the Common Centaur. Though the Delta missions realize a small amount of performance gain, this is primarily a commonality upgrade focused on affordability, flexibility, and a streamlined supplier chain for the DoD customer. At this time, the 5m Delta Upper stage is not included.
With the above plan for reworking RL10B-2s for Atlas the inventory [sic], RL-10 engines run out in the 2018 timeframe. ULA sees this as an opportunity to cut in a brand new 25klb thrust class upper stage engine option, and it has approached an array of engine vendors for concepts. A newly manufactured block of RL-10Cs remains an option. Larger than 25klb thrust creates challenges for the existing EELV fleet, including a particular challenge for a key Heavy GEO missions, which are essentially thrust insensitive, but would be penalized for the higher weight associated with a higher thrust engine.
The proposed 5m-diameter ACES upper stage is being pursued in addition to the Common Centaur.

Offline edkyle99

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RL-10 is an (and cheap!) engine

NO, with the end of the SSME contract all of the prices are going through the roof.  Take what you knew and multiply by 4.

How would a new engine contract address this problem?

 - Ed Kyle

Offline TrueBlueWitt

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Sounds like they want RL-10B-2 performance in an RL-10A-4-2 package. 
How much would payloads to GTO increase for Atlas V with NGE?
I didn't see a mass target for the new engine.. did I miss something?
Jim.. would this be to retrofit existing US.. or for a new common(ACES?) US?
   Effectively, both are possible and under consideration.

Read Barr & Kutter 2010 (pg.4):

Quote
ULA has been focusing on common Atlas and Delta upper stage upgrades as the next steps in our EELV evolution. Some confusion can exist because ULA is pursuing two separate upper stage upgrades. The Common Centaur is focused on the Air Force, NASA science, and commercial requirements with the goal of replacing the Delta IV 4m Upper Stage with the Centaur to achieve greater commonality and to realize cost savings across the EELV fleet. Tied to this upgrade is the rework of the large number of inventory RL10B-2 engines into a new common RL10C variant that captures the best of the B-2 and A-4, and can be used on Atlas V, and potentially the Common Centaur. Though the Delta missions realize a small amount of performance gain, this is primarily a commonality upgrade focused on affordability, flexibility, and a streamlined supplier chain for the DoD customer. At this time, the 5m Delta Upper stage is not included.
With the above plan for reworking RL10B-2s for Atlas the inventory [sic], RL-10 engines run out in the 2018 timeframe. ULA sees this as an opportunity to cut in a brand new 25klb thrust class upper stage engine option, and it has approached an array of engine vendors for concepts. A newly manufactured block of RL-10Cs remains an option. Larger than 25klb thrust creates challenges for the existing EELV fleet, including a particular challenge for a key Heavy GEO missions, which are essentially thrust insensitive, but would be penalized for the higher weight associated with a higher thrust engine.
The proposed 5m-diameter ACES upper stage is being pursued in addition to the Common Centaur.

Interesting read for anyone that hasn't seen ULA's proposals.

http://www.ulalaunch.com/site/docs/publications/ULA-Innovation-March-2010.pdf

Page 12  Figure 21 is illuminating as far as Stage Failure  rates with multiple engines and engine out. 
I assume NGE would reduce the 1 of 1 Failure rates?

Single engine(1 of 1) shows 79 failures per 100,000
3 of 4(engine out) shows Stage failure rate of only 5 per 100,000
« Last Edit: 10/17/2010 04:26 am by TrueBlueWitt »

Offline clongton

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RL-10 is an (and cheap!) engine

NO, with the end of the SSME contract all of the prices are going through the roof.  Take what you knew and multiply by 4.

SSME contract isn't ending. It will be the powerplant for the SLS.
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I started my career on the Saturn-V F-1A engine

Offline Antares

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Which (1) has only occurred in the last few days and (2) isn't definite.
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline clongton

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Which (1) has only occurred in the last few days and (2) isn't definite.

(1) Correct, but it's a fact none-the-less
(2) Yes it is. It can *only* be the SSME for the core stage engine because:
From the Authorization Act Sect 304: "The Administrator shall, to the extent practical utilize –"
(1)(B): "Space Shuttle-derived components and Ares I components that use existing United States propulsion systems, including liquid fuel engines, external tank," etc.

That language allows for only 3 possible engines; SSME, J-2X and RL-10. The J-2X and RL-10 are upper stage engines only, leaving the sole remaining main engine to be the SSME.
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Offline MP99

Is this excluding RS-68 for technical reasons (base heating) or because of the definition of "United States propulsion systems"?

cheers, Martin

Offline clongton

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Is this excluding RS-68 for technical reasons (base heating) or because of the definition of "United States propulsion systems"?

cheers, Martin

I cannot answer that because I didn't write the text. All I can say is that those who did write the text are fully aware of the thermal environment next to the SRB's and that an ablative nozzle RS-68 would not survive to MECO. Whether or not that knowledge influenced their choice of wording is not mine to say.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline MP99

Chuck,

OK, thanks - sometimes the answer you get is more interesting than the question that was asked (lawyer-type nit-picking over syntax)! I'm still not sure that the language itself precludes RS-68, although Ed did post this recently:-

In addition, RS-68 uses components from Japan's Mitsubishi Heavy Industries, dropping it from the "all U.S." category.


I was just trying to understand if the language in the bill gave NASA any wriggle room on core engine choice (other than the gaping "to the extent practical").

cheers, Martin
« Last Edit: 10/21/2010 05:00 pm by MP99 »

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